A consortium of researchers led by the University of Sydney developed a novel vascular graft from a combination of tropoelastin and polyglycerol sebacate that mimics the structure of living blood vessels. This vascular graft facilitates de novo formation of a structurally appropriate elastin-containing intima-media region following implantation in mice.
Native arteries contain a distinctive intima-media composed of organized elastin and an adventitia containing mature collagen fibrils. Elastin-containing structures in the intima-media region encompass the elastic lamellae and internal elastic lamina and are crucial for normal arterial function.
If necessary, a vascular graft can be used to repair the damaged artery. Autologous vascular grafts from the patient’s saphenous veins, radial arteries, and internal mammary arteries are considered the gold-standard grafts. Commercially available synthetic grafts are made from expanded polytetrafluoroethylene and polyethylene terephthalate. They show markedly decreased patency over time when used as small-diameter vascular grafts (1–6 mm), due to thrombosis and restenosis. Moreover, their non-degradable nature does not support complete arterial regeneration.
About the study
The researchers fabricated a non-porous biodegradable vascular graft from a combination of tropoelastin (TE) and polyglycerol sebacate (PGS), a highly elastic and degradable biomaterial. Mixing over 30% w/v TE with PGS in ratios of 30:70, 50:50, 70:30, and 100:0 TE: PGS resulted in the formation of electrospun scaffolds, which were named TE30, TE50, TE70, and TE100, respectively. TE50 and TE70 each supported the proliferation of endothelial cells of the human umbilical vein and smooth muscle cells of the human coronary artery, as well as the expression of functional artery-related proteins.
The study describes TE-PGS scaffold fabrication, characterization, selection, implantation into the abdominal aorta in mice, and a remodelling into a neoartery. TE50 was selected for implantation into the abdominal aorta of the mouse, because it was less prone to thrombosis.
The non-porous TE50 acted as a framework for stimulating distinctive regeneration profiles in the intima-media and the adventitia. After implantation in the abdominal aorta of the mouse, the graft developed distinct cellular and extracellular matrix profiles that approximated the native adventitia and intima-media by 8 weeks. By 8 months, the graft completely degraded, forming a neoartery. Adventitia was found to contain mature collagen. An internal elastic lamina similar to that of the mouse abdominal aorta also formed after 8 months.
The authors concluded that their results demonstrated the potential of TE50 as a functional vascular graft capable of achieving complete arterial regeneration.
The study was published in the scientific journal Advanced Materials. Wang Z et al. Rapid Regeneration of a Neoartery with Elastic Lamellae. Advanced Materials 2022; 34: 2205614 (Open Access) https://onlinelibrary.wiley.com/doi/10.1002/adma.202205614